Foil bearings are hydrodynamic or aerodynamic bearings in which in the case of an unloaded bearing a bearing surface supporting the shaft or supporting the pivoting rotor is formed by a thin and wear-resistant top foil which for its part is supported by an elastic corrugated foil arranged between the top foil and bearing housing wall. In operation a hydrodynamic or aerodynamic film bearing the shaft or the rotor is formed between the shaft and the top foil. Only during starting and stopping procedures is there direct moving contact between the shaft and the top foil. Foil bearings of the described type are preferably used for lightly loaded shafts running at high speed, for example compressors, gas turbines, turbo chargers and the like.
In the case of known foil bearings of the described type, the holder of the foil arrangement in the bearing housing, which on the one hand ensures a securing of the same in particular in rotational direction, but on the other hand is supposed to allow heat-induced compensatory movements of the foil arrangement, has proved to be very difficult from a design and production standpoint.
Foil bearings are known from U.S. Pat. No. 5,902,049, for example, in which case the foil arrangement consisting of outer foils, corrugated foils and top foils is supported in the circumferential direction on one side on a bolt fastened in suitable manner, for example by welding on the inside of the bearing housing. In the process, the end edge of the radially inner top foil is fastened on the bolt via tack or spot welding, while the associated end edges of the other foil layers are only supported on one side on the bolt. The end edges secured in this manner averted from the end edges of the corrugated and top foils run freely, so that the foil arrangement of this known bearing is essentially only sufficiently secured for one rotational direction. The described holder of the foil arrangement in the bearing housing is on the one hand extremely expensive from a design and production standpoint. On the other hand the bearing is limited in its use due to the on one side securing of the bearing arrangement.
Against this background, this disclosure addresses the problem of creating a foil bearing in which a securing of the foil arrangement is realized that is simple in design and production and suitable for both rotational directions.